The purpose of this project is to investigate the incidence, determinants, and morbid sequelae of low birth weight in 20 rural villages in Assiut Governorate in Upper Egypt. The project includes the following major components: a complete census of the 20 villages to record demographic characteristics and environmental conditions of each household; weekly surveillance of births, deaths, and migrations to update the census; prospective monitoring of all deliveries with collection of data about the pregnancy and delivery and measurement of infant birth weights; and prospective weekly surveillance of all children in the villages aged 36 months or younger for symptoms and signs of diarrhea, acute respiratory infection, measles, malnutrition and growth disorders, or other diseases. Analyses will focus on evaluation of maternal, household, and obstetric characteristics as risk factors for low birth weight and on the relationships between birth weight, child morbidity, and growth patterns. The project will also include a service component, in which mothers, newborns, and children with specified morbid symptoms will be referred to community clinics which will be established in each community.